1. Field of the Invention
The present invention relates generally to improvements in the design and operation of article handling apparatus and is particularly useful in the environment of article handling devices that use a suction-type article handling mechanism.
2. Description of the Prior Art
Most prior art article handling mechanisms, more specifically referred to in the description of the present invention as being in the environment of a point-of-sale (POS) article dispenser, rely on a multitude of motors, switches and solenoids for moving various portions of the handling mechanism, and handling of the articles themselves, such as packaged products. Most such machines require one motor, switch and/or solenoid dedicated for each row, column or type of article or package to be handled or dispensed therefrom. Such machines generally suffer from numerous disadvantages, such as poor reliability due to mechanical failures, as well known by those skilled in this art.
U.S. Pat. No. 5,240,139 represents a significant improvement in article handling devices. It describes the use of a negative air pressure lifter (i.e., article pickup or handling mechanism), which uses suction, i.e., a reduced or so-called “negative” air pressure created by a partial vacuum, for making a secure contact to an article to be retrieved by entering the open top of an article storage bin located in a refrigerated storage area of a vending machine. Although robotic, and specifically suction-type lifting mechanisms are in common use in factory settings, where space limitations are generally relaxed, their use in tight confines, such as an article vending machine, has not gained wide acceptance. Due to the greater reliability and versatility of vending machines of the type which utilizes suction technology for grasping and moving selected articles, it would be desirable to develop new techniques and methods for the operation and control of such machines, as well as for other more generalized article handling mechanisms.
Article contact detection is provided in the forenoted U.S. Pat. No. 5,240,139 by a mechanical or electromechanical proximity switch mounted at the article pickup end of the negative air pressure lifter.
It would be desirable to avoid the use of a proximity switch type of sensor at the article pickup end of the lifter, most notably because of the necessity of providing to the pickup head power and signal carrying conductors associated with the switch. Such conductors not only present obstacles to the freedom of movement of the pickup head, but also present reliability problems due to their potential for breakage. However, even if a “remotely-positioned” type of product contact sensor is provided, care must be taken to ensure that it is simple and reliable.
Furthermore, a vacuum breaker would also be desirable in a vending machine having a suction-type article handler, in order to facilitate a “quick release” of the product at the end of the dispensing cycle. U.S. Pat. No. 5,957,326 entitled APPARATUS FOR RETRIEVING RANDOMLY ORGANIZED ARTICLES, describes a vending apparatus having a suction-type article handler and a vacuum breaker. A pickup head having a plurality of suction cups mounted thereon (in order to help ensure the retrieval of one of a plurality of randomly organized articles for a storage bin) is lowered into the storage bin as suction is applied to the cups. After the passage of a predetermined amount of time, the machine controller causes the pickup head to start being removed from the bin. While the pickup head is being removed, a vacuum sensing assembly coupled to each suction cup determines if more than one of the suction cups has an article attached thereto (i.e., article contact is assumed in response to the sensing of vacuum in the hose coupled to a given suction cup). If more than one suction cup has an article adhered thereto, the machine controller causes a valve assembly 81 to release vacuum from all of the suction cups except one. Furthermore, when the product pickup head reaches a certain predetermined “delivery” position, the valve assembly 81 causes the vacuum to be released so that the product can be dropped. No mechanical connection is shown between the product pickup head and the valve assembly 81, so it is logical to assume that the valve 81 is activated by and electronic signal.
PCT patent publication WO 99/12132 entitled VENDING MACHINE discloses a vending machine having an articulated arm for positioning an article gripping suction hose into a freezer for retrieving articles to be dispensed. It teaches the use of both an electromechanically operated proximity switch at the article gripper head for turning the vacuum source on when the gripper makes contact with the product, as well as the use of a position sensor for advising the machine controller to energize a vacuum breaker when the gripperhead reaches a predetermined position indicative of the product reaching the dispensing area.